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Sept 7 Weather Review Weather map basics Energy that Drives the Storms (chapter 2) More Weather Maps ( Isopleths ) Classwork (HW#3) Homework #4. Tonight. Hrcn Earl Visible. Weather Review. Hrcn Earl Infrared (IR). Weather Review. Hrcn Earl Enhanced IR. Weather Review.
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Sept 7 • Weather Review • Weather map basics • Energy that Drives the Storms (chapter 2) • More Weather Maps (Isopleths) • Classwork (HW#3) • Homework #4 Tonight
Hrcn EarlVisible Weather Review
Hrcn Earl Infrared (IR) Weather Review
Hrcn Earl Enhanced IR Weather Review
Hrcn Earl Visible Weather Review
“Hurricane Force Wind Gusts” • Criteria: 1-minute sustained winds ≥ 74 mph • Peak 3 to 5-second gusts ~ 30% higher • Exerted Force: proportional to the square of the wind speed • Force from a 74 mph gust = 14.0 psf • Force from a 96 mph gust = 23.6 psf • 69% higher. Weather Review
TS HermineVisible Weather Review
TS HermineInfrared Weather Review
TS HermineEnhance Infrared Weather Review
TS HermineRadar Weather Review
TS HermineQPF Weather Review
Station model 80 021 -23 63
Station model 80 021 -23 63
Station model 80 021 -23 63 Temperature Surface: ºF Upper air: ºC
Station model 80 021 -23 63 Dew point temperature Surface: ºF Upper air: ºC
Station model 80 021 -23 63 Totalsky cover ** Depicted by shading in circle
Station model 80 021 -23 63 Current weather conditions ** If blank, “no weather”
Station model 80 021 -23 63 Wind direction – of wind toward center
Station model 80 021 -23 63 Wind speed Long barb = 10 knots Short barb = 5 knots Flag = 50 knots ** Notice range of wind speeds (i.e., 28-32 knots)
Station model 80 021 -23 63 Sea level pressure **If first number is 5 or greater, then place 9 in front --Otherwise, place 10 in front **Place decimal point between last two numbers
Station model 80 021 -23 63 Change in surface pressure during last 3 hours ** In tenths of mb ** Line describes how pressure changes over time from left to right
Example 1 • Temperature: 76 ºF • Dew point: 65 ºF • Sky cover: Completely overcast • Current weather: Light rain • Wind direction and speed: Southwest at 15 knots • Sea level pressure: 995.3 mb • Pressure tendency: Increase of 1.6 mb; rising steadily 76 953 +16 65
Example 2 • Temperature: 10ºF • Dew point: 8ºF • Sky cover: 7/10 or 8/10 • Current weather: Snow shower • Wind direction and speed: North at 3-7 knots • Sea level pressure: 1010.5 mb • Pressure tendency: Decrease of 0.4 mb; falling, then steady 10 105 -4 8
High & Low Pressure Systems • Air pressure Patterns are main organizing feature • Circulation in Northern Hemisphere • Clockwise around Highs (H) • CCW around Lows (L) • Clouds & Precip around Lows • Temperature patterns result from latitude, wind flow and cloud cover
Plotting Fronts • Boundary between Different Air Masses • Types of Fronts
CHAPTER 2 ENERGY THAT DRIVES THE STORMS
ENERGY AND HEAT TRANSFER • Energy is the capacity to do work on some form of matter • Potential energy: The total amount of energy stored in any object is capable of doing • Kinetic energy: Any moving substance possesses energy of motion
Cold Air vs. Warm Air Slower and closer together ….. Faster and farther apart Fig. 2.1, p. 37
ENERGY AND HEAT TRANSFER • Atoms and molecules have kinetic energy due to their motion (heat energy) • Most important energy in terms of weather and climate is radiant energy from the sun • Air temperature is a measure of the average kinetic energy of its molecules
ENERGY AND HEAT TRANSFER • Heat is energy being transferred from one object to another because of a temperature difference • After heat is transferred, it is stored as internal energy • Heat is transferred in the atmosphere by • Conduction • Convection • Radiation
ENERGY AND HEAT TRANSFER • Latent heat: energy required to change a substance, such as water, from one state to another • Evaporation is a cooling process due to absorption of latent heat from the environment • Condensation is a warming process due to a release of latent heat to the environment
Changes of State Fig. 2.2, p. 37
ENERGY AND HEAT TRANSFER • Conduction: the transfer of heat from molecule to molecule • Always flows from warmer to colder • Air is an extremely poor conductor of heat
ENERGY AND HEAT TRANSFER • Convection: transfer of heat by the mass movement of a fluid (water or air) • Example: Pan of boiling water • Convection circulation: warm air expands and rises then cools and sinks • Thermal cell, convection, thermals
Thermal Circulations Fig. 2.5, p. 40
Thermal Circulations Fig. 2.6, p. 40